# eval(): 字符串转算数表达式
print(eval('10 + 10'))
# print(eval('10 + "10"'))

# str/list/tuple三者之间的转换
str1 = '[1,2,3,4]'
print(list(str1))
print(eval(str1))
print(list((1, 2, 3, 4, 5)))

# 集合
set1 = set('abc')
print(set1)
set2 = set([3, 2, 1])
print(set2)
